Various proposals have been suggested to provide a closed mold cavity for maintaining foam precursors under pressure during the foaming process so as to eliminate foam leakage around the filling nozzle.
U.S. Pat. No. 4,030,267 discloses a mold packaging system wherein a lid carries an inlet duct with a ring of elastic material. When the lid is closed, a plug is selectively connected on the inlet duct to engage the ring to prevent the escape of foam from the mold cavity.
U.S. Pat. No. 3,354,408 discloses a charge fitting for a plastic molding apparatus which includes an elastomeric valve disk that engages a nozzle for injecting plastic material into a cavity between first and second mold parts. In this arrangement the nozzle is sealed as it is directing plastic into the mold apparatus. The fitting will seal the charge within the mold when the nozzle is removed therefrom. While suitable for its intended purpose, the molding apparatus does not include a preformed shell on one of the mold cavity parts. In such cases, a rear wall mounted pour head access port has to bridge the shell. The charge fitting in the U.S. Pat. No. 3,354,408 patent is not configured to address the problem of how to bridge such a preformed shell component during the molding process.
U.S. Pat. No. 4,033,710 discloses a fill nozzle arrangement for directing thermoplastic material into a pour mold cavity. The fill nozzle includes a pair of shutter jaws that are made of flexible material. The jaws close around an insert tube for injecting a foaming agent into the foam material during the molding process.
U.S. Pat. Nos. 4,303,720; 4,420,447 and 4,477,504 disclose processes for forming instrument panel composite structures in which an insert is supported on a lid for a mold cavity in which a skin is located. In these processes, the material is poured into the mold cavity when the lid is removed and the mold is enclosed to allow the foam precursors to expand and fill a foam cavity that will form a foam layer on the back side of the preformed shell of the composite structure.
U.S. Pat. No. 4,743,188 discloses an apparatus for sealing a pour head in a mold wherein a sleeve is integrally formed on the preformed shell and located within an access port formed through the wall of the mold cavity port through which a pour head extension is mounted. The latter is selectively sealingly clamped and unclamped with respect to the shell sleeve by an inflatable seal clamp which is formed as a surrounding annular ring with a pressurizable passage connected to a source of selectively applied pressure.